Unknown gunmen have shot dead at least one foreigner and three Afghans in the heart of the capital Kabul. Police officials said they did not know the identity of the victims or the motive behind the attack, which comes amid rising violence in Afghanistan. One police official said one foreigner was killed in the attack, but a second police official said he had received conflicting reports that either one or two foreigners had been killed. Private television station Tolo TV said two foreigners were killed in the attack in the upmarket Sher Pur area of Kabul where many foreigners live. The second police officer said the victims worked for the worldwide express delivery and cargo firm, DHL. The attack comes less than a week after a female British aid worker was killed in another part of Kabul.